I have full checked my Starcom out and all is working now.
The Zumo 550 is now connected to an iPhone via Bluetooth, and the Zumo is connected to the Starcom with Bluetooth, and I can now make calls and be heard. Ended up having to buy a 2nd Bluetooth module to connect the passenger phone!!
The iPhone is hard wired to the music input at the same time, so I get the music directly to the Starcom and it works brilliantly.
I did upgrade the Zumo recently and now a couple of issues more appeared, when I power up the bike the Zumo turns on (connected through the BMW headstock connector) at which stage it doesnt find any bluetooth devices, and even when trying to manually connect it doesnt work, turning just the Zumo off then on again it finds both the phone and the starcom BT.
Also when the nav commands come through they are heard over the music, a few seconds latter after the directions come through the music tuns off for a few seconds, not critical just a bit anoying.
I suspect the Starcom cable to the Zumo is the fault, or noice from the bike when running the cable.
But its working and I can be heard now on the phone......